Can anyone tell me how to set up SPF and Postfix?
I installed the libspf2 package and also a few perl modules that
are supposed to be there for SPF to work.

I get a reject message from another server I'm sending an email to:

Code:

The administrator of the domain wm-mw.org may have incorrectly configured its SPF record. This is a common cause of mistakes.

Here's what you can do: Contact the wm-mw.org postmaster and tell them that they need to change wm-mw.org's SPF record so that it authorizes smtp-o-1.netrevolution.com. For example, they could change the record to something like

v=spf1 a ptr a:smtp-o-1.netrevolution.com -all
If you refer your postmaster to this web page, they should be able to solve the problem.

I don't see anywhere in Postfix configuration about setting up SPF.
I use Webmin to manage my server...

What exactly do you want to do with your mailserver? Do you run a mailing list or try to send emails on wm-mw.org's behalf? Is wm-mw.org your domain? If not, you cannot configure the domain's SPF record._________________Death by snoo-snoo!

Yes, we are wm-mw.org... and we own our servers. We never had a problem til
now like this. I guess SPF is becoming more common now.
Anyway, we try to send email to certain people and we get the error message sent
back to us. The emails are sent to them from our server using Postfix.
I see under BIND there is a Mail Server category under localhost.
In there is a Add Mail Server Record area. Is that where I add the domain we
are trying to send to?
No, we are not a mailing list company. Just an affiliate program for musicians.

smtp-o-1.netrevolution.com tried to send an email claiming it came from wm-mw.org, though your SPF record [1] states, that netrevolution's smtp is not authorized to do this.
This happens, when your mailserver tries to send an email to, lets say user@netrevolution.com, and this email address is an alias for, lets say user@otherdomain.com. Netrevolutions smtp then tried to forward this email, but kept the original "MAIL FROM: whatever@wm-mw.org". otherdomain.com's smtp then checked your SPF record [1] and decided to reject the email, because smtp-o-1.netrevolution.com is not authorized to send emails with an envelope FROM address which includes your domain.

It is a matter of debate which party has a misconfiguration here. Maybe netrevolution shouldn't use your domain as MAIL FROM address. Personally, I think, that otherdomain.com's mailserver is too strict by rejecting those emails directly. The only thing you can do, without debating with netrevolution's and/or otherdomain's IT staff, is to loosen up your SPF record, which is a nameserver issue, not postfix.

Yes, I was in Webmin this morning and looking at the BIND DNS server.
I got as far as seeing Add Sender Permitted From Record under localhost.
I just have no idea what to enter there.
This is a screenshot:

Hi, "localhost" does not sound right, and +all does not match "-all" in the query result I get for your domain [1].
Your domain is handled by the nameservers ns1.no-ip.com to ns5.no-ip.com, so you seem to have an account at no-ip.com? If you don't know, ask the one who registered your domain. It is those nameservers which need to be configured appropriately.